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Pre-workout is one of the best supplements to help power you through a tough workout. Weight lifters, bodybuilders, powerlifters, and even athletes all use pre-workout to help keep them sharp and focused while performing. Most pre-workouts contain a powerful combination of stimulants to give you energy and focus while training. However, pre-workouts do not just contain stimulants. Most pre-workouts contain nitric oxide boosters, creatine, BCAA’s, and other ingredients that help performance, muscle growth, and recovery.

In fact, pre-workout has been around since the early 1980s. Back then, some pre-workouts contained dangerous ingredients that were quickly banned from sale. However, in recent years pre-workout has gone through some serious changes. Now most pre-workouts contain ingredients backed through research, and they do not contain proprietary blends. Although, it all depends on which pre-workout you use.

In recent years, intermittent fasting has emerged in the health and fitness industry. So many of those who lift weights or train want to know if pre-workout will break their fast. Most people like to workout early in the morning, however that is when most are in their fasting window. It becomes a problem, and the last thing you want to do is accidentally be breaking your fast by consuming pre-workout. This article is going to be explaining the ingredients found in most pre-workouts, looking at nutritional facts, and discussing if pre-workout will truly break your fast.

Does Pre-Workout Break My Fast?

Yes, most pre-workouts will break your fast. This is due to them containing proteinogenic amino acids and sweeteners which will cause an insulin response within the body. Most pre-workouts contain proteinogenic amino acids like leucine, isoleucine, and valine which have been shown to trigger insulin spikes within the body. So, these amino acids would signal your brain and body that you have just consumed food, and would break your fast. By consuming pre-workout you would be cancelling most of the benefits of intermittent fasting like autophagy, gut rest, and increased metabolism.

Also, most pre-workouts contain calories and carbohydrates due to the flavoring for taste. Naturally, ingredients like caffeine, BCAA’s, and creatine taste pretty bad. So, most pre-workouts contain sweeteners with flavors such as candy apple, blue raspberry, etc. to help mask these ingredients! The problem is these sweeteners would “technically” be breaking your fast as well. Artificial sweeteners have been shown to trigger an insulin spike and activate digestion within the body.

Pre-Workout Nutritional Facts

First, let’s look at the nutritional facts of a pre-workout supplement. It is extremely important to check the nutritional label and ingredient list for the products you consume while fasting. You need to make sure it contains zero calories, zero macronutrients, and no ingredients that will be breaking your fast. Such as artificial sweeteners.

This nutritional label is from the popular pre-workout called Pre Jym. I have nothing against this pre-workout, and in fact it is my personal favorite to consume when I am not fasting. However, you can see that pre jym would clearly break your fast.

It contains 15 calories per scoop with 4 grams of carbohydrates and 2 grams of sugar. So these macronutrients would cause an insulin response and break your fast. Also, it contains proteinogenic amino acids like leucine, isoleucine, and valine, which would break your fast as well.

Lastly, you must look at the ingredient on the products you want to consume. The main ingredients here are dextrose, natural and artificial flavors, and sucralose. So, the issue here would be dextrose and the artificial sweetener sucralose. Both of these ingredients would be breaking your fast.

What About Zero Calorie Pre-Workouts?

I often get asked about zero calorie supplements such as zero calorie pre-workouts. However, just because it is zero calories does not mean it is acceptable to consume while fasting! It is super important to understand this concept. You do not want to be ruining your fast by consuming zero calorie products that may still be breaking your fast.

Let’s look at a zero calorie pre-workout like C4. This pre-workout by Cellucor is very popular, and is zero calories. It contains 0 calories, 0 grams of sugar, and <1 gram of carbohydrates. So, most would assume this is okay to consume while fasting.

However, you must look at the ingredients! It contains amino acids like L Tyrosine and Arginine, which will break your fast by causing an insulin response within the body. Also, it contains artificial sweeteners like sucralose which breaks your fast as well.

That is why it is super important to check the nutritional facts and ingredient list. Even though this pre-workout has 0 calories, it still would technically be breaking your fast.

The Problem With BCAA’s While Fasting

Brained chained amino acids or BCAA’s are fantastic! They are great for recovery and to build muscle. Amino acid are especially important around training and workouts, because they will help supply your body with the fuel it needs to repair and rebuild. However, you do not want to consume BCAA’s while fasting. Check out my full article on BCAA’s while fasting here.

Like I said, the main issue with pre-workouts is that they contain amino acids. More specifically, essential proteinogenic amino acids. These amino acids cause an insulin response within the body. This is due to the fact that these amino acids are responsible for activating protein synthesis. Meaning, they are used by your body for building protein and building muscle. Especially the essential amino acid Leucine. Research shows that Leucine activates protein synthesis pathways in the brain, and will signal to your brain that you have been fed. Thus, breaking your fast.

So, proteinogenic amino acids are a no-no while fasting. These include the 9 essential amino acids such as valine, isoleucine, leucine, threonine, tryptophan, phenylalanine, methionine, lysine, and histidine. Also, you want to avoid the 11 nonessential amino acids as well such as serine, glycine, asparagine, proline, alanine, arginine, cysteine, aspartic acid, tyrosine, glutamine, and glutamic acid.

Pre-Workout Supplements That Won’t Break Your Fast

My advice for those who want to workout or train while fasting is to make your own pre-workout. One that will not break your fast. Although, you shouldn’t consume the 20 amino acids listed above while fasting..you CAN consume non proteinogenic supplements while fasting.

Non proteinogenic supplements contain 0 calories, 0 macronutrients, 0 artificial flavors or sweeteners, and will not break your fast. This is because non proteinogenic supplements are not used by the body for protein synthesis. So, they will not cause an insulin response.

These include supplements like betaine, creatine, beta-alanine, D-aspartic acid, carnitine, and creatine. These supplements will not trigger an insulin response within the body and contain zero calories. So, they are acceptable to consume and will not break your fast! Listed below are supplements that are acceptable to consume while fasting. If you want to still take supplements for your training while fasted, then I recommend creating your own stack with those listed below.

Final Thoughts

I know it can be hard to get through tough workouts without consuming pre-workout, especially if you are fasting. However, there are a few things you can do to avoid this issue. I always first recommend working out during your feeding window to avoid this issue. However, I understand this is not always do-able.

If you must workout while fasted, then I recommend using some non proteinogenic supplements as your pre-workout. This includes caffeine, beta alanine, creatine, etc. These supplements are acceptable, and will make you feel like you just consumed pre-workout! You could even drink black coffee as a pre-workout option. Even Arnold Schwarzenegger and Frank Zane used to drink coffee prior to training, way before pre-workout even existed!

Remember to check the nutritional facts and ingredient list, because you do not want to be consuming anything that will potentially be breaking your fast. Make sure to stay clear of most pre-workouts while fasted, because the amino acids and sweeteners will break your fast. Even most zero calorie options will break your fast. Stick with only non proteinogenic supplements while fasting, such as those listed above.

Hi my name is John, or better known around these parts as The Muscle Master. I started my fitness journey 10 years ago which led me to pursue my Doctoral Degree in Physical Therapy. I am a fitness enthusiast with up to date knowledge on all things anatomy and exercise related. I wanted to share my passion and knowledge so much that I decided to create this website to share all things related to your health, muscle, and fitness goals.